EP3259291B1

EP3259291B1 - An impact modifier and a polymer composition comprising the same

Info

Publication number: EP3259291B1
Application number: EP15828592.4A
Authority: EP
Inventors: Michael T. PETR; Carlos A. Cruz
Original assignee: Rohm and Haas Co
Current assignee: Rohm and Haas Co
Priority date: 2014-12-22
Filing date: 2015-12-17
Publication date: 2021-07-14
Anticipated expiration: 2035-12-17
Also published as: WO2016106055A1; CN107001543B; EP3259291A1; BR112017012913B1; JP6655621B2; US10316126B2; US20170362367A1; CN107001543A; BR112017012913A2; JP2017538021A; KR102480143B1; KR20170101220A

Description

Field of Invention

The disclosure relates to an impact modifier and a polymer composition comprising the same.

Background of the Invention

In an impact modifier, the impact resistance comes from the constituent crosslinked, low glass transition (T_g) rubber. The characteristics of this rubber directly affect the ability of the modifier to provide ductility in a base polymer during impact. One of these characteristics is crosslink density because it controls the stiffness of the rubber and its ability to cavitate. Often, in an impact modifier, the crosslink density is controlled by the addition of a crosslinker into the low T_g polymer. The distribution of the crosslink density is directly proportional to the distribution of the crosslinker in the rubber. The rubber is also often made with a shot process, whereby all the monomer is charged to the reactor and then its polymerization is initiated, in order to keep the standing monomer concentration high and the branching in the rubber low; therefore, the crosslinker distribution, and thus, the crosslink density distribution is entirely dependent on the reactivity ratios of the rubber monomer and crosslinker.
Butyl, ethyl, 2-ethylhexyl and other acrylic esters are often the rubber monomers of choice, and either a multi-functional acrylate or allyl methacrylate (ALMA) are often the crosslinkers of choice. ALMA has the advantage of different reactivities of the allyl double bond and the methacrylate double bond. Therefore, ALMA produces less backbiting loops in the rubber and more graftlinks to the shell. However the higher reactivity of the methacrylate double bond in ALMA compared to that of the acrylate double bond causes the crosslink density to be high at the beginning of each shot and then decrease to zero at the end of the shot. Thus, there is a need for a more effective crosslinker to use in an acrylic impact modifier made by the shot process. EP0927616 discloses an impact modified PVC exhibiting improved low temperature fusion.

Summary of the Invention

The disclosure provides an impact modifier composition comprising one or more core/shell polymers which comprise a crosslinked core having from 98 to 99.9 wt% units derived from butyl acrylate and from 0.1 to 2 wt% units derived from a crosslinker containing a vinylically unsaturated moiety with an acrylate free radical reactivity ratio from 0.8 to 1.2 and one or more non-acrylate vinylically unsaturated moiety(ies) with an acrylate free radical reactivity ratio(s) greater than 1, wherein the crosslinked core has a swell ratio in THF between 7 and 15 and a glass transition temperature, Tg, of less than or equal to 10 °C; and a shell having 100 wt% units derived from methyl methacrylate monomers and having a Tg of greater than 20 °C.
The disclosure provides a polymer composition comprising an impact modifier and a base polymer.

Detailed Description of the Invention

The disclosure provides an impact modifier and a polymer composition comprising the impact modifier.
(Meth)acrylate means acrylate, methacrylate, or combinations of acrylate and methacrylate. For example, the term methyl (meth)acrylate may mean solely methyl methacrylate, solely methyl acrylate or a combination of methyl methacrylate and methyl acrylate.
Free radical reactivity ratio, as used herein, means the free radical propagation rate constant from the acrylate monomer(s) to the acrylate monomer(s) relative to the free radical propagation rate constant from the acrylate monomer(s) to any other vinylically unsaturated moiety in the crosslinker.
The disclosure provides an impact modifier composition comprising one or more core/shell polymers which comprise a crosslinked core having from 98 to 99.9 wt% units derived from one or more acrylate monomers and from 0.1 to 2 wt% units derived from a crosslinker containing a vinylically unsaturated moiety with an acrylate free radical reactivity ratio from 0.8 to 1.2 and one or more non-acrylate vinylically unsaturated moiety(ies) with an acrylate free radical reactivity ratio(s) greater than 1, wherein the crosslinked core has a swell ratio in THF between 7 and 15 and a glass transition temperature, Tg, of less than or equal to 10 °C; and a shell having 100 wt% units derived from (meth)acrylate monomers and having a Tg of greater than 20 °C.
The disclosure provides a polymer composition comprising from greater than 10 to 30 wt% of one or more impact modifier compositions and from 70 to 90 wt% of any structural base polymers selected from the group consisting of but not limited to polyesters, styrenic polymers, polymethacrylates, polyvinylchloride, polycarbonate, polyamides, copolymers and blends thereof and combinations thereof.
The one or more core/shell polymers comprises a crosslinked core having from 98 to 99.9 wt% units derived from one or more acrylate monomers. All individual values and subranges from 98 to 99.9 wt% are included and disclosed herein; for example the amount of units derived from one or more acrylate monomers can range from a lower limit of 98, 98.4, 98.8, 99.2 or 99.6 wt% to an upper limit of 98.2, 98.6, 99.0, 99.4, 99.8 or 99.9 wt%. For example, the amount of units derived from one or more acrylate monomers in the crosslinked core may be from 98 to 99.9 wt%, or in the alternative, from 98 to 99 wt%, or in the alternative, from 98.9 to 99.9 wt%, or in the alternative, from 98.5 to 99.5 wt%.
Any C₁ to C₂₀ alkyl acrylate monomer may be used in forming the crosslinked core. Exemplary acrylate monomers include butyl acrylate.
The disclosure further provides the impact modifier and polymer composition according to any embodiment disclosed herein, except that the acrylate monomer used in the crosslinked core is butyl acrylate.
The one or more core/shell polymers comprises a crosslinked core having from 0.1 to 2 wt% units derived from a crosslinker containing a vinylically unsaturated moiety with an acrylate free radical reactivity ratio from 0.8 to 1.2 and one or more non-acrylate vinylically unsaturated moiety(ies) with an acrylate free radical reactivity ratio(s) greater than 1. All individual values and subranges from 0.1 to 2 wt% are included and disclosed herein; for example, the amount of units derived from the crosslinker can range from a lower limit of 0.1, 0.5, 0.9, 1.3 or 1.7 wt% to an upper limit of 0.3, 0.7, 1.1, 1.5, 1.9 or 2 wt%. For example, the amount of units derived from the crosslinker may be from 0.1 to 2 wt%, or in the alternative, from 0.1 to 1 wt%, or in the alternative, from 1 to 2 wt%, or in the alternative, from 0.5 to 1.5 wt%.
The vinylically unsaturated moiety has an acrylate free radical reactivity ratio from 0.8 to 1.2. All individual values and subranges from 0.8 to 1.2 are included and disclosed herein; for example, the acrylate free radical reactivity ratio can range from a lower limit of 0.8, 0.9, 1.0 or 1.1 to an upper limit of 0.9, 1.0, 1.1, or 1.2.
Crosslinker used in the crosslinked core is allyl acrylate.
The crosslinked core has a glass transition temperature, Tg, of less than or equal to 10 °C. All individual values and subranges of less than or equal to 10 °C are included and disclosed herein. For example, the Tg of the crosslinked core may be less than or equal to 10 °C, or in the alternative, less than or equal to 0 °C, or in the alternative, less than or equal to -10 °C, or in the alternative, less than or equal to -20 °C.
The disclosure further provides the impact modifier and polymer composition according to any embodiment disclosed herein, except that the crosslinked core comprises 98 to 99.9 wt% units derived from butyl acrylate and from 0.1 to 2 wt% units derived from a crosslinker.
The disclosure further provides the impact modifier and polymer composition according to any embodiment disclosed herein, except that the crosslinked core comprises from 99.1 to 99.8 wt% units derived from butyl acrylate and from 0.2 to 0.9 wt% units derived from a crosslinker.
The disclosure further provides the impact modifier and polymer composition according to any embodiment disclosed herein, except that the crosslinked core comprises 98 to 99.9 wt% units derived from butyl acrylate and from 0.1 to 2 wt% units derived from allyl acrylate.
The disclosure further provides the impact modifier and polymer composition according to any embodiment disclosed herein, except that the crosslinked core comprises from 99.1 to 99.8 wt% units derived from butyl acrylate and from 0.2 to 0.9 wt% units derived from allyl acrylate.
The crosslinked core has a swell ratio in THF between 7 and 15. All individual values and subranges from 7 to 15 are included and disclosed herein; for example the swell ratio of the crosslinked core in THF can range from a lower limit of 7, 9, 11 or 13 to an upper limit of 8, 10, 12, 14 or 15. For example, the swell ratio of the crosslinked core in THF can be from 7 to 15, or in the alternative, from 7 to 11, or in the alternative, from 11 to 15, or in the alternative, from 9 to 13.
The one or more core/shell polymers comprise a shell having 100 wt% units derived from (meth)acrylate monomers.
The shell has a Tg of greater than 20 °C. All individual values and subranges from greater than 20 °C are included and disclosed herein. For example, the Tg of the shell may be greater than 20 °C, or in the alternative, greater than 30 °C, or in the alternative, greater than 40 °C, or in the alternative, greater than 60 °C.
Any alkyl (meth)acrylate monomer may be used in the shell of the one or more core/shell polymers. Exemplary (meth)acrylate monomers include C₁-C₂₀ alkyl methacrylates, including but not limited to methyl methacrylate.
The polymer composition comprises from greater than 10 to 30 wt% of one or more impact modifier compositions according to any embodiment disclosed herein.
The polymer composition comprise from 70 to 90 wt% of a structural base polymer selected from the group consisting of polyesters, styrenic polymers, polymethacrylates, polyvinylchloride, polycarbonate, polyamides, copolymers and blends thereof and combinations thereof.
The structural base polymers are selected from the group consisting of polyesters, styrenic polymers, polymethacrylates, polyvinylchloride, polycarbonate, polyamides, copolymers and blends thereof and combinations thereof.
In a particular embodiment, the structural base polymer is polyvinylchloride.
Emulsion polymerization reaction vessels, or reactors, are well known and any such reactor may be used. Such reactors, include but are not limited to those discussed in, for example, D. C. Blackley, Emulsion Polymerization (Wiley, 1975).
Suitable emulsifiers include anionic surfactants, cationic surfactants, nonionic surfactants, zwitterionic surfactants, and mixtures thereof. In some embodiments, one or more anionic surfactant is used, optionally in a mixture with one or more nonionic surfactant. Some suitable anionic surfactants include, for example, alkyl sulfates, alkyl sulfonates, alkylaryl sulfates, alkylaryl sulfonates, and mixtures thereof. Some suitable nonionic surfactants include, for example, alkyl polyoxyalkylene nonionic surfactants, aryl polyoxyalkylene nonionic surfactants, polyoxyalkylene block copolymers, and mixtures thereof.
In the practice of the present invention, a reactive mixture is provided in a reaction vessel. The reactive mixture contains water, one or more emulsifier, one or more monomer, and one or more initiator. The ingredients of the reactive mixture may be brought together in any manner. For example, two or more of the ingredients of the reactive mixture, or portions thereof, may be mixed together before the mixture of those ingredients or portions thereof is placed into the reaction vessel. For example, any ingredients or portions thereof that are not mixed together outside of the reaction vessel may be added simultaneously or sequentially to the reaction vessel. Any combination of the above methods of providing the ingredients of the reactive mixture may be used.
After a reactive mixture is present in the reaction vessel, conditions are provided in which the reactive mixture undergoes emulsion polymerization. For example, conditions will be provided as needed for the initiator to form one or more free radical. That is, depending on the initiator used, for example, the reaction mixture may be heated, or a reductant may be added, or the reactive mixture may be exposed to radiation, or a combination thereof. Also, it is contemplated that other conditions that allow emulsion polymerization to succeed (such as, for example, emulsification of monomer, concentration of monomer, concentration of initiator). will also be provided.
The conditions in which the reactive mixture undergoes emulsion polymerization will be established simultaneously with the introduction of the reactive mixture into the reaction vessel. For example, if the ingredients of the reactive mixture are not added simultaneously, in some embodiments the conditions in which the reactive mixture undergoes emulsion polymerization may be established simultaneously with the introduction of the final ingredient of the reactive mixture into the reaction vessel.
The conditions in which the reactive mixture undergoes emulsion polymerization will be established after the introduction of the reactive mixture into the reaction vessel. For example, all of the ingredients of the reactive mixture may be provided in the reaction vessel, and then the contents of the reaction vessel may be heated to a temperature at which the initiator forms one or more free radical.
In conventional shot emulsion polymerization processes, the emulsion polymerization process includes at least one stage that includes at least one shot. In some shot embodiments, at least one shot introduces 10% or more of the total monomer of the entire emulsion polymerization process, by weight based on the weight of the total monomer for the entire emulsion polymerization process. In some shot embodiments, most (greater than 50%) or all of the monomer for the emulsion polymerization process is added to the reaction vessel as part of one or more shots, and each shot introduces 10% or more of the total monomer of the entire emulsion polymerization process, by weight based on the weight of the total monomer for the entire emulsion polymerization process.

Examples

The following examples illustrate the present invention but are not intended to limit the scope of the invention.
Inventive Impact Modifier Compositions 1, 2A, 2B, 2c, and 3-7 were made using a conventional three shot process, with the amount of crosslinker varied amongst the Impact Modifier Compositions, as shown in Table 1. Butyl acrylate was used as the one or more acrylate monomers used in the core of each of the Impact Modifier Compositions. The shell was made from methyl methacrylate.
Comparative Impact Modifier Composition 1 was made using a conventional three shot process and comprised a core of 99.29 wt% units derived from butyl acrylate and 0.71 wt% units derived from allyl methacrylate.

Comparative Impact Modifier Composition 2 was made using a conventional three shot process and comprised a core of 99.55 wt% units derived from butyl acrylate and 0.45 wt% units derived from allyl methacrylate. Inv. Ex 4 and Inv. Ex 5 and Inv. Ex 6 and Inv Ex 7 are not according to the invention.

Table 1

Impact Modifier Examples	wt % crosslinker in Impact Modifier Core	Swell Ratio
Comp. Ex. 1	0.71 wt% ALMA	7.2
Comp. Ex. 2A	0.45 wt% ALMA	10.1
Inv. Ex. 1	0.2 allyl acrylate	14.2
Inv. Ex. 2A	0.4 allyl acrylate	9.6
Inv. Ex. 2B	0.4 allyl acrylate	9.5
Inv. Ex. 2C	0.4 allyl acrylate	9.7
Inv. Ex. 3	0.6 allyl acrylate	8.0
Inv. Ex. 4	0.9 allyl acrylate	6.6
Inv. Ex. 5	1.2 allyl acrylate	5.8
Inv. Ex. 6	0.4 allyl acrylamide	9.8
Inv. Ex. 7	0.56 allyloxyethyl acrylate	10.9

Each of the Inventive and Comparative Impact Modifier Compositions were added to PVC at levels of 4 phr and 4.5 phr to produce the Polymer Composition Examples to produce Inventive Polymer Composition Examples 1, 2A, 2B, 2C and 3-7 and Comparative Polymer Composition Examples 1 and 2, respectively. Table 2 provides the Izod Notched Impact results for each of these polymer compositions.

Table 2

Polymer Composition Examples	Notched Izod Impact
	% Impact Modifier in Polymer Composition
	4 phr	4.5 phr
Comp. Ex. 1	0	70
Comp. Ex. 2	5	75
Inv. Ex. 1	20	100
Inv. Ex. 2A	50	100
Inv. Ex. 2B	63	100
Inv. Ex. 2C	70	100
Inv. Ex. 3	10	100
Inv. Ex. 4	20	90
Inv. Ex. 5	10	-
Inv. Ex. 6	20	100
Inv. Ex. 7	10	82

Test Methods

Test methods include the following:
Swell ratio is measured by dissolving 5 wt% polymer in THF. The solution is then centrifuged to separate the insoluble portion. After that, the insoluble portion is weighed, dried, and then weighed again, and the swell ratio is defined as the ratio of the wet weight to the dry weight.

Samples are prepared by first preparing a master batch of PVC. In this particular case, the following formulation was used:

Component	Specifics	parts per hundred (phr) of PVC
PVC	FORMOLON 622S	100.00
Heat Stabilizer	ADVASTAB TM-181FS	1.2
Lubrication package	ADVALUBE B-3314	2.7
Lubricating process aid	PARALOID K-175	0.5
Process Aid	PARALOID K-400	1.0
Filler	TiO₂	9.0
Filler	UFT(CaCO₃)	3.0
Impact Modifier	See Table 1	See Table 1

PARALOID K-175 is an acrylic polymer processing aids which is commercially available from The Dow Chemical Company (Midland, MI, USA). PARALOID K-400 is an acrylic copolymer processing aids which is commercially available from The Dow Chemical Company. ADVASTAB TM-181FS is a methyltin based heat stabilizer which is commercially available from PMC Group (Mount Laurel, New Jersey, USA). ADVALUBE B-3314 is an ester based lubricant which is commercially available from PMC Group. FORMOLON 622S is a polyvinylchloride resin which is commercially available from Formosa Plastics Corporation, U.S.A. (Livingston, New Jersey, USA). UFT (CaCO₃) is commercially available from Omya, Inc. (Cincinnati OH, USA).
Components were added using the standard protocol for PVC powder blending in a Henschel-type blender. The resulting powder blends were allowed to stand for at least 24 hours at room temperature. A portion of the powder (usually about 220 grams) was then melt processed in an electric two-roll mill (COLLIN Mill Type # WW 150 p). The mill temperature was set at 190 °C with the front roll mill speed at 26 RPM and the back at 21 RPM. The polymer blend was melt processed for a total time of 5 minutes after fusion occurred. The sample was then placed in a 0.125 inch x 8.5 inch x 10 inch mold, by suitably folding the mass, and pressed in a RELIABLE press at 190 °C for 3 minutes at 15 tons and then 2 minutes at 45 tons. Cooling was accomplished under 45 tons for an additional 3-4 minutes. Samples were cut into test strips with dimensions according to the ASTM D-256 standard, notched with a mechanical notching tool and allowed to equilibrate at room temperature for 24 hours
Testing was carried out with a 50-lb hammer in an Izod pendulum tester. Twenty specimens per sample were tested. The results were divided into brittle breaks and ductile (hinged) breaks, depending on whether, respectively, the sample hit by the hammer was cleanly broken into two portions as the crack traveled through the notch or if the sample remained as a single entity, where the two portions divided by the crack remained connected by a "hinge" of the plastic material. The percentage of ductile-type breaks for each set of specimens was recorded. If any anomalies, such as an observable delamination, were detected after the specimen was broken, that particular specimen was disregarded from the final calculations and the percentage of ductile breaks corrected accordingly.

Claims

An impact modifier composition comprising one or more core/shell polymers which comprise:
a crosslinked core having from 98 to 99.9 wt% units derived from butyl acrylate and from 0.1 to 2 wt% units derived from allyl acrylate crosslinker containing a vinylically unsaturated moiety with an acrylate free radical reactivity ratio from 0.8 to 1.2 and one or more non-acrylate vinylically unsaturated moiety(ies) with an acrylate free radical reactivity ratio(s) greater than 1, wherein the crosslinked core has a swell ratio in THF between 7 and 15 and a glass transition temperature, Tg, of less than or equal to 10 °C; and

a shell having 100 wt% units derived from methyl methacrylate monomers and having a Tg of greater than 20 °C.
The impact modifier composition according to claim 1, wherein the crosslinked core comprises from 99.1 to 99.8 wt% units derived from butyl acrylate and from 0.2 to 0.9 wt% units derived from allyl acrylate.
A polymer composition comprising:
from greater than 10 to 30 wt% of one or more impact modifier compositions according to any one of claims 1-2; and

from 70 to 90 wt% of any structural base polymers selected from the group consisting of but not limited to polyesters, styrenic polymers, polymethacrylates, polyvinylchloride, polycarbonate, polyamides, copolymers and blends thereof and combinations thereof.